5.4.6 page fault while running btfrs scrub

* 5.4.6 page fault while running btfrs scrub
@ 2019-12-30 12:36 Josef Miegl
  2019-12-30 22:16 ` Josef Miegl
  2019-12-31 20:09 ` Josef Miegl
  0 siblings, 2 replies; 3+ messages in thread
From: Josef Miegl @ 2019-12-30 12:36 UTC (permalink / raw)
  To: linux-btrfs

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Quick rundown:
	1. made a new luks encrypted partition on an ssd
	2. formatted the volume with btrfs
	3. systemd mounts the fs with discards enabled
	4. filled about 45% of the available space
	5. btrfs reported no free space available
	6. ran btrfs balance start /
	7. balance quit with no space available message, but it fixed
	the free space issue
	8. supposed there was something wrong with the fs and ran
	btrfs scrub start /

# uname -a
Linux t420 5.4.6-arch3-1 #1 SMP PREEMPT Tue, 24 Dec 2019 04:36:53 +0000 x86_64 GNU/Linux

# btrfs --version
btrfs-progs v5.4

dmesg:
[  391.487379] BTRFS info (device dm-1): scrub: started on devid 1
[  520.224044] BUG: stack guard page was hit at 00000000e297e985 (stack is 000000006621d119..000000007c53ae63)
[  520.225356] kernel stack overflow (page fault): 0000 [#1] PREEMPT SMP NOPTI
[  520.226858] CPU: 2 PID: 748 Comm: btrfs Not tainted 5.4.6-arch3-1 #1
[  520.228268] Hardware name: LENOVO 4180A21/4180A21, BIOS CBET4000 4.9-2176-g2195f7af23 06/22/2019
[  520.229901] RIP: 0010:memcpy_erms+0x6/0x10
[  520.231401] Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe
[  520.234391] RSP: 0018:ffffb5c5c07478b8 EFLAGS: 00010206
[  520.235797] RAX: ffffb5c5c0747ac8 RBX: ffff9a3b4d6aba90 RCX: fffffffffffffacc
[  520.237256] RDX: 0000000000000004 RSI: ffff9a3b4d6abffc RDI: ffffb5c5c0748000
[  520.238716] RBP: 0000000000000009 R08: 0000000000010000 R09: ffff9a3b4d6aba80
[  520.240288] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000
[  520.241865] R13: dead000000000122 R14: dead000000000100 R15: ffff9a3b62c55800
[  520.243466] FS:  00007f4d38999700(0000) GS:ffff9a3b67480000(0000) knlGS:0000000000000000
[  520.245105] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  520.246767] CR2: ffffb5c5c0748000 CR3: 000000024efa2003 CR4: 00000000001606e0
[  520.248476] Call Trace:
[  520.250245]  scrub_find_csum+0xf9/0x150 [btrfs]
[  520.252026]  scrub_stripe+0x8c6/0x1040 [btrfs]
[  520.253803]  ? wait_woken+0x70/0x70
[  520.255604] Modules linked in: ext4 mbcache jbd2 uas usb_storage mousedev ccm algif_aead des_generic libdes arc4 algif_skcipher cmac md4 algif_hash af_alg snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_codec_generic intel_rapl_msr intel_rapl_common iwldvm i915 mac80211 x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_intel snd_intel_nhlt kvm_intel libarc4 btusb uvcvideo snd_hda_codec btrtl i2c_algo_bit iTCO_wdt iwlwifi btbcm videobuf2_vmalloc iTCO_vendor_support drm_kms_helper btintel videobuf2_memops videobuf2_v4l2 kvm tpm_tis videobuf2_common bluetooth thinkpad_acpi tpm_tis_core irqbypass snd_hda_core intel_cstate tpm videodev intel_uncore drm psmouse pcspkr snd_hwdep nvram intel_rapl_perf ecdh_generic ledtrig_audio cfg80211 input_leds i2c_i801 ecc snd_pcm mc battery ac crc16 rng_core intel_gtt e1000e snd_timer evdev agpgart mac_hid syscopyarea sysfillrect snd sysimgblt fb_sys_fops coreboot_table soundcore lpc_ich rfkill pkcs8_key_parser ip_tables x_tables btrfs libcrc32c
[  520.255650]  crc32c_generic xor raid6_pq dm_crypt dm_mod sr_mod cdrom sd_mod crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel ahci serio_raw libahci atkbd libps2 aesni_intel libata sdhci_pci crypto_simd cqhci cryptd sdhci glue_helper scsi_mod mmc_core ehci_pci ehci_hcd i8042 serio
[  520.271062] ---[ end trace 9be44e8a9868703f ]---
[  520.273520] RIP: 0010:memcpy_erms+0x6/0x10
[  520.275994] Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe
[  520.281108] RSP: 0018:ffffb5c5c07478b8 EFLAGS: 00010206
[  520.283611] RAX: ffffb5c5c0747ac8 RBX: ffff9a3b4d6aba90 RCX: fffffffffffffacc
[  520.286069] RDX: 0000000000000004 RSI: ffff9a3b4d6abffc RDI: ffffb5c5c0748000
[  520.288508] RBP: 0000000000000009 R08: 0000000000010000 R09: ffff9a3b4d6aba80
[  520.290970] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000
[  520.293434] R13: dead000000000122 R14: dead000000000100 R15: ffff9a3b62c55800
[  520.295894] FS:  00007f4d38999700(0000) GS:ffff9a3b67480000(0000) knlGS:0000000000000000
[  520.298379] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  520.300870] CR2: ffffb5c5c0748000 CR3: 000000024efa2003 CR4: 00000000001606e0

The SSD is Samsung EVO 860 500GB. I've never seen this kind of problem
when using btrfs so far. Perhaps it's some rare fs corruption?

Josef Miegl

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